bims-rimeca 2023-05-28 papers

bims-rimeca

Biomed News

on RNA methylation in cancer

Issue of 2023–05–28
fourteen papers selected by
Sk Ramiz Islam, Saha Institute of Nuclear Physics

m6A methyltransferase METTL3 facilitates multiple myeloma cell growth through the m6A modification of BZW2.
N6-methyladenosine helps Apostichopus japonicus resist Vibrio splendidus infection by targeting coelomocyte autophagy via the AjULK-AjYTHDF/AjEEF-1α axis.
N6-methyladenosine modified LINC00901 promotes pancreatic cancer progression through IGF2BP2/MYC axis.
METTL14 Facilitates the Metastasis of Pancreatic Carcinoma by Stabilizing LINC00941 in an m6A-IGF2BP2-Dependent Manner.
METTL3 and STAT3 form a positive feedback loop to promote cell metastasis in hepatocellular carcinoma.
NAT10, an RNA Cytidine Acetyltransferase, Regulates Ferroptosis in Cancer Cells.
Expression pattern analysis of m6A regulators reveals IGF2BP3 as a key modulator in osteoarthritis synovial macrophages.
YTHDF2 inhibition potentiates radiotherapy antitumor efficacy.
METTL3-mediated m6A mRNA modification was involved in cadmium-induced liver injury.
RNA demethylase ALKBH5 suppresses tumorigenesis via inhibiting proliferation and invasion and promoting CD8+ T cell infiltration in colorectal cancer.
Identification of m7G-Related LncRNA Signature for Predicting Prognosis and Evaluating Tumor Immune Infiltration in Pancreatic Adenocarcinoma.
FTO Promotes the Stemness of Gastric Cancer Cells.
Hyperglycemia and O-GlcNAc transferase activity drive a cancer stem cell pathway in triple-negative breast cancer.
Novel methylation-related long non-coding RNA clinical outcome prediction method: the clinical phenotype and immune infiltration research in low-grade gliomas.

Ann Hematol. 2023 May 24.

m6A methyltransferase METTL3 facilitates multiple myeloma cell growth through the m6A modification of BZW2.

Xiaoqing Huang, Zhiyong Yang, Yanwen Li, Xingxing Long.

  N6-methyladenosine (m6A) methyltransferase-like 3 (METTL3) has been confirmed to be involved in multiple myeloma (MM) progression, and basic leucine zipper and W2 domains 2 (BZW2) is considered to be a regulator for MM development. However, whether METTL3 mediates MM progression by regulating BZW2 remains unclear. The messenger RNA (mRNA) and protein levels of METTL3 and BZW2 in MM specimens and cells were determined using quantitative real-time PCR and western blot analysis. Cell proliferation and apoptosis were assessed by cell counting kit 8 assay, 5-ethynyl-2'-deoxyuridine assay, colony formation assay, and flow cytometry. Methylated RNA immunoprecipitation-qPCR was used to detect the m6A modification level of BZW2. Xenograft tumor models were constructed to confirm the effect of METTL3 knockdown on MM tumor growth in vivo. Our results showed that BZW2 was upregulated in MM bone marrow specimens and cells. BZW2 downregulation reduced MM cell proliferation and promoted apoptosis, while its overexpression enhanced MM cell proliferation and inhibited apoptosis. METTL3 was highly expressed in MM bone marrow specimens, and its expression was positively correlated with BZW2 expression. BZW2 expression was positively regulated by METTL3. Mechanistically, METTL3 could upregulate BZW2 expression by modulating its m6A modification. Additionally, METTL3 accelerated MM cell proliferation and restrained apoptosis via increasing BZW2 expression. In vivo experiments showed that METTL3 knockdown reduced MM tumor growth by decreasing BZW2 expression. In conclusion, these data indicated that METTL3-mediated the m6A methylation of BZW2 to promote MM progression, suggesting a novel therapeutic target for MM.

Keywords:  Apoptosis; BZW2; METTL3; Multiple myeloma; Proliferation; m6A

DOI:  https://doi.org/10.1007/s00277-023-05283-6
Commun Biol. 2023 May 20. 6(1): 547

N6-methyladenosine helps Apostichopus japonicus resist Vibrio splendidus infection by targeting coelomocyte autophagy via the AjULK-AjYTHDF/AjEEF-1α axis.

Jiqing Liu, Yina Shao, Dongdong Li, Chenghua Li.

N6-Methyladenosine (m6A) modification is one of the most abundant post-transcriptional modifications that can mediate autophagy in various pathological processes. However, the functional role of m6A in autophagy regulation is not well-documented during Vibrio splendidus infection of Apostichopus japonicus. In this study, the inhibition of m6A level by knockdown of methyltransferase-like 3 (AjMETTL3) significantly decreased V. splendidus-induced coelomocyte autophagy and led to an increase in the intracellular V. splendidus burden. In this condition, Unc-51-like kinase 1 (AjULK) displayed the highest differential expression of m6A level. Moreover, knockdown of AjULK can reverse the V. splendidus-mediated autophagy in the condition of AjMETTL3 overexpression. Furthermore, knockdown of AjMETTL3 did not change the AjULK mRNA transcript levels but instead decreased protein levels. Additionally, YTH domain-containing family protein (AjYTHDF) was identified as a reader protein of AjULK and promoted AjULK expression in an m6A-dependent manner. Furthermore, the AjYTHDF-mediated AjULK expression depended on its interaction with translation elongation factor 1-alpha (AjEEF-1α). Altogether, our findings suggest that m6A is involved in resisting V. splendidus infection via facilitating coelomocyte autophagy in AjULK-AjYTHDF/AjEEF-1α-dependent manner, which provides a theoretical basis for disease prevention and therapy in A. japonicus.

DOI: https://doi.org/10.1038/s42003-023-04929-5
Genes Dis. 2023 Mar;10(2): 554-567

N6-methyladenosine modified LINC00901 promotes pancreatic cancer progression through IGF2BP2/MYC axis.

Wan-Xin Peng, Fei Liu, Jia-Hong Jiang, Hang Yuan, Ziqiang Zhang, Liu Yang, Yin-Yuan Mo.

  Accumulating evidence indicates that RNA methylation at N6-methyladenosine (m6A) plays an important regulatory role in gene expression and aberrant mRNA m6A modification is often associated with a variety of cancers. However, little is known whether and how m6A-modification impacts long non-coding RNA (lncRNA) and lncRNA-mediated tumorigenesis, particularly in pancreatic ductal adenocarcinoma (PDAC). In the present study, we report that a previously uncharacterized lncRNA, LINC00901, promotes pancreatic cancer cell growth and invasion and moreover, LINC00901 is subject to m6A modification which regulates its expression. In this regard, YTHDF1 serves as a reader for the m6A modified LINC00901 and downregulates the LINC00901 level. Notably, two conserved m6A sites in LINC00901 are critical to the recognition of LINC00901 by YTHDF1. Finally, RNA sequencing (RNA-seq) and gene function analysis revealed that LINC00901 positively regulates MYC through upregulation of IGF2BP2, a known RNA binding protein that can enhance MYC mRNA stability. Together, our results suggest that there is a LINC00901-IGF2BP2-MYC axis through which LINC00901 promotes PDAC progression in an m6A dependent manner.

Keywords:  IGF2BP2; LINC00901; MYC; N6-methyladenosine modification (m6A); PDAC; YTHDF1

DOI:  https://doi.org/10.1016/j.gendis.2022.02.014
J Cancer. 2023 ;14(7): 1117-1131

METTL14 Facilitates the Metastasis of Pancreatic Carcinoma by Stabilizing LINC00941 in an m6A-IGF2BP2-Dependent Manner.

Jiawei Lu, Lanting Yu, Ni Xie, Ying Wu, Baiwen Li.

  Pancreatic adenocarcinoma (PC), one of the most fatal diseases, usually generates a poor prognosis in advanced stages. N6-methyladenosine modification has emerged as a crucial participant in tumor development and recurrence. Methyltransferase-like 14 (METTL14), as a core member of methyltransferases, is involved in tumor progression and metastasis. However, the potential mechanism by which METTL14 regulates long noncoding RNAs (lncRNAs) in PC remains unclear. RNA immunoprecipitation (RIP), methylated RNA immunoprecipitation quantitative PCR (MeRIP-qPCR), and fluorescence in situ hybridization (FISH) were used to explore the underlying mechanisms. In our study, we found that METTL14 expression was upregulated in PC patients, and was associated with poor prognosis. In vitro and in vivo experiments, knocking down METTL14 suppressed tumor metastasis. RNA-seq and bioinformatics analyses were used to identify LINC00941 as the downstream target of METTL14. Mechanistically, LINC00941 was upregulated by METTL14 in an m6A-dependent way. LINC00941 was recruited and recognized by IGF2BP2. METTL14 enhanced the affinity of IGF2BP2 for LINC00941, while IGF2BP2 promoted the stabilization of LINC00941, which contributed to the migration and invasion of PC cells. Overall, our research revealed that METTL14 promoted the metastasis of PC through m6A modification of LINC00941. Targeting the METTL14-LINC00941-IGF2BP2 axis may provide promising therapeutic approaches for PC.

Keywords:  IGF2BP2; LINC00941; METTL14; N6-methyladenosine; metastasis; pancreatic carcinoma

DOI:  https://doi.org/10.7150/jca.84070
Cell Commun Signal. 2023 May 25. 21(1): 121

METTL3 and STAT3 form a positive feedback loop to promote cell metastasis in hepatocellular carcinoma.

Bowen Liu, Jinling Cao, Biting Wu, Kaixuan Hao, Xiangyun Wang, Xin Chen, Zhifa Shen.

   BACKGROUND: It is well-established that most Hepatocellular carcinoma (HCC) patients die of metastasis, yet the potential mechanisms orchestrating metastasis remain poorly understood. Current evidence suggests that the dysregulation of METTL3-mediated m6A methylation modification is closely associated with cancer progression. STAT3 is an oncogenic transcription factor that reportedly plays a central role in the occurrence and development of HCC. However, the relationship between METTL3 and STAT3 in HCC metastasis remains unclear.
METHODS: The relationship between METTL3 expression and the survival of HCC patients was assessed by online tools GEPIA and Kaplan-Meier Plotter. Western blotting, Tissue microarray (TMA), and immunohistochemistry (IHC) staining were used to evaluate the expression levels of METTL3 and STAT3 in HCC cell lines and metastatic and non-metastatic tissues. Methylated RNA immunoprecipitation (MeRIP), MeRIP sequencing (MeRIP-seq), qRT-PCR, RNA immunoprecipitation (RIP), Western blotting and luciferase reporter gene assay were utilized to clarify the mechanism of METTL3 regulating STAT3 expression. Immunofluorescence staining, Western blotting, qRT-PCR, Co-immunoprecipitation (Co-IP), IHC staining, TMA and Chromatin immunoprecipitation (ChIP) assay were performed to explore the mechanism of STAT3 modulating METTL3 localization. Cell viability, wound healing and transwell assay, and orthotopic xenograft model were used to evaluate the role of METTL3-STAT3 feedback loop in the promotion of HCC metastasis in vitro and in vivo.
RESULTS: METTL3 and STAT3 are both abundantly expressed in high-metastatic HCC cells and tissues. Moreover, a positive correlation was found between the expression of STAT3 and METTL3 in HCC tissues. Mechanistically, METTL3 could induce the m6A modification of STAT3 mRNA, and then promote the translation of m6A-contained STAT3 mRNA by interacting with the translation initiation machinery. In contrast, STAT3 promoted nuclear localization of METTL3 via transcriptionally upregulating WTAP, a vital member of the methyltransferase complex, and facilitated the methyltransferase function of METTL3. METTL3 and STAT3 form a positive feedback loop to accelerate HCC metastasis in vitro and in vivo.
CONCLUSIONS: Our findings reveal a novel mechanism of HCC metastasis and uncover the METTL3-STAT3 feedback signaling as a potential target for the anti-metastatic treatment of HCC. Video Abstract.

Keywords:  Hepatocellular carcinoma; METTL3; Metastasis; STAT3; m6A methylation modification

DOI:  https://doi.org/10.1186/s12964-023-01148-7
Antioxidants (Basel). 2023 May 18. pii: 1116. [Epub ahead of print]12(5):

NAT10, an RNA Cytidine Acetyltransferase, Regulates Ferroptosis in Cancer Cells.

Mahmood Hassan Dalhat, Hani Choudhry, Mohammad Imran Khan.

  Recently, we reported that N-acetyltransferase 10 (NAT10) regulates fatty acid metabolism through ac4C-dependent RNA modification of key genes in cancer cells. During this work, we noticed ferroptosis as one of the most negatively enriched pathways among other pathways in NAT10-depleted cancer cells. In the current work, we explore the possibility of whether NAT10 acts as an epitranscriptomic regulator of the ferroptosis pathway in cancer cells. Global ac4C levels and expression of NAT10 with other ferroptosis-related genes were assessed via dotblot and RT-qPCR, respectively. Flow cytometry and biochemical analysis were used to assess oxidative stress and ferroptosis features. The ac4C-mediated mRNA stability was conducted using RIP-PCR and mRNA stability assay. Metabolites were profiled using LC-MS/MS. Our results showed significant downregulation in expression of essential genes related to ferroptosis, namely SLC7A11, GCLC, MAP1LC3A, and SLC39A8 in NAT10-depleted cancer cells. Further, we noticed a reduction in cystine uptake and reduced GSH levels, along with elevated ROS, and lipid peroxidation levels in NAT10-depleted cells. Consistently, overproduction of oxPLs, as well as increased mitochondrial depolarization and decreased activities of antioxidant enzymes, support the notion of ferroptosis induction in NAT10-depleted cancer cells. Mechanistically, a reduced ac4C level shortens the half-life of GCLC and SLC7A11 mRNA, resulting in low levels of intracellular cystine and reduced GSH, failing to detoxify ROS, and leading to increased cellular oxPLs, which facilitate ferroptosis induction. Collectively, our findings suggest that NAT10 restrains ferroptosis by stabilizing the SLC7A11 mRNA transcripts in order to avoid oxidative stress that induces oxidation of phospholipids to initiate ferroptosis.

Keywords:  NAT10; RNA acetylation; ROS; SLC7A11; ferroptosis

DOI:  https://doi.org/10.3390/antiox12051116
J Transl Med. 2023 05 22. 21(1): 339

Expression pattern analysis of m6A regulators reveals IGF2BP3 as a key modulator in osteoarthritis synovial macrophages.

Yuheng Lu, Hongbo Zhang, Haoyan Pan, Zhicheng Zhang, Hua Zeng, Haoyu Xie, Jianbin Yin, Wen Tang, Rengui Lin, Chun Zeng, Daozhang Cai.

   BACKGROUND: Disruption of N6 methyl adenosine (m6A) modulation hampers gene expression and cellular functions, leading to various illnesses. However, the role of m6A modification in osteoarthritis (OA) synovitis remains unclear. This study aimed to explore the expression patterns of m6A regulators in OA synovial cell clusters and identify key m6A regulators that mediate synovial macrophage phenotypes.
METHODS: The expression patterns of m6A regulators in the OA synovium were illustrated by analyzing bulk RNA-seq data. Next, we built an OA LASSO-Cox regression prediction model to identify the core m6A regulators. Potential target genes of these m6A regulators were identified by analyzing data from the RM2target database. A molecular functional network based on core m6A regulators and their target genes was constructed using the STRING database. Single-cell RNA-seq data were collected to verify the effects of m6A regulators on synovial cell clusters. Conjoint analyses of bulk and single-cell RNA-seq data were performed to validate the correlation between m6A regulators, synovial clusters, and disease conditions. After IGF2BP3 was screened as a potential modulator in OA macrophages, the IGF2BP3 expression level was tested in OA synovium and macrophages, and its functions were further tested by overexpression and knockdown in vitro.
RESULTS: OA synovium showed aberrant expression patterns of m6A regulators. Based on these regulators, we constructed a well-fitting OA prediction model comprising six factors (FTO, YTHDC1, METTL5, IGF2BP3, ZC3H13, and HNRNPC). The functional network indicated that these factors were closely associated with OA synovial phenotypic alterations. Among these regulators, the m6A reader IGF2BP3 was identified as a potential macrophage mediator. Finally, IGF2BP3 upregulation was verified in the OA synovium, which promoted macrophage M1 polarization and inflammation.
CONCLUSIONS: Our findings revealed the functions of m6A regulators in OA synovium and highlighted the association between IGF2BP3 and enhanced M1 polarization and inflammation in OA macrophages, providing novel molecular targets for OA diagnosis and treatment.

Keywords:  IGF2BP3; Osteoarthritis; Synovial macrophages; m6A regulators

DOI:  https://doi.org/10.1186/s12967-023-04173-9
Cancer Cell. 2023 May 15. pii: S1535-6108(23)00163-0. [Epub ahead of print]

YTHDF2 inhibition potentiates radiotherapy antitumor efficacy.

Liangliang Wang, Xiaoyang Dou, Shijie Chen, Xianbin Yu, Xiaona Huang, Linda Zhang, Yantao Chen, Jiaai Wang, Kaiting Yang, Jason Bugno, Sean Pitroda, Xingchen Ding, Andras Piffko, Wei Si, Chao Chen, Hualiang Jiang, Bing Zhou, Steven J Chmura, Cheng Luo, Hua Laura Liang, Chuan He, Ralph R Weichselbaum.

  RNA N6-methyladenosine (m6A) modification is implicated in cancer progression. However, the impact of m6A on the antitumor effects of radiotherapy and the related mechanisms are unknown. Here we show that ionizing radiation (IR) induces immunosuppressive myeloid-derived suppressor cell (MDSC) expansion and YTHDF2 expression in both murine models and humans. Following IR, loss of Ythdf2 in myeloid cells augments antitumor immunity and overcomes tumor radioresistance by altering MDSC differentiation and inhibiting MDSC infiltration and suppressive function. The remodeling of the landscape of MDSC populations by local IR is reversed by Ythdf2 deficiency. IR-induced YTHDF2 expression relies on NF-κB signaling; YTHDF2 in turn leads to NF-κB activation by directly binding and degrading transcripts encoding negative regulators of NF-κB signaling, resulting in an IR-YTHDF2-NF-κB circuit. Pharmacological inhibition of YTHDF2 overcomes MDSC-induced immunosuppression and improves combined IR and/or anti-PD-L1 treatment. Thus, YTHDF2 is a promising target to improve radiotherapy (RT) and RT/immunotherapy combinations.

Keywords:  MDSCs; NF-kB; Radiation; YTHDF2; m6A

DOI:  https://doi.org/10.1016/j.ccell.2023.04.019
Environ Pollut. 2023 May 24. pii: S0269-7491(23)00889-8. [Epub ahead of print] 121887

METTL3-mediated m6A mRNA modification was involved in cadmium-induced liver injury.

Wenxue Li, Mingxue Tan, Huiqi Wang, Ziwei Wang, Yaqin Pang, Rongfang Yang, Shiyuan Zhong, Xinhong Pan, Shen Chen, Qing Wang, Daochuan Li, Yongmei Xiao, Wen Chen, Liping Chen.

  Cadmium is an environmental pollutant that has extensive deleterious effects. However, the mechanisms underlying the hepatotoxicity induced by long-term exposure to cadmium remained undefined. In the present study, we explored the role of m6A methylation in the development of cadmium-induced liver disease. We showed a dynamic change of RNA methylation in liver tissue from mice administrated with cadmium chloride (CdCl2) for 3, 6 and 9 months, respectively. Particularly, the METTL3 expression was declined in a time-dependent manner, associated with the degree of liver injury, indicating the involvement of METTL3 in hepatotoxicity induced by CdCl2. Moreover, we established a mouse model with liver-specific over-expression of Mettl3 and administrated these mice with CdCl2 for 6 months. Notably, METTL3 highly expressed in hepatocytes attenuated CdCl2-induced steatosis and liver fibrosis in mice. In vitro assay also showed METTL3 overexpression ameliorated the CdCl2-induced cytotoxicity and activation of primary hepatic stellate cells. Furthermore, transcriptome analysis identified 268 differentially expressed genes both in mice liver tissue treated with CdCl2 for 3 months and 9 months. Among them, 115 genes were predicted to be regulated by METTL3 determined by m6A2Target database. Further analysis revealed the perturbation of metabolic pathway, glycerophospholipid metabolism, ErbB signaling pathway, Hippo signaling pathway, and choline metabolism in cancer, and circadian rhythm, led to hepatotoxicity induced by CdCl2. Collectively, our findings reveal new insight into the crucial role of epigenetic modifications in hepatic diseases caused by long-term exposure to cadmium.

Keywords:  Cadmium; Hepatotoxicity; METTL3; RNA methylation

DOI:  https://doi.org/10.1016/j.envpol.2023.121887
Transl Oncol. 2023 May 22. pii: S1936-5233(23)00069-4. [Epub ahead of print]34 101683

RNA demethylase ALKBH5 suppresses tumorigenesis via inhibiting proliferation and invasion and promoting CD8+ T cell infiltration in colorectal cancer.

Jing Ge, Sheng-Lu Liu, Jing-Xiu Zheng, Yu Shi, Ying Shao, Yu-Jing Duan, Rui Huang, Li-Jun Yang, Tao Yang.

   BACKGROUND: ALKBH5 belongs to the ALKB family consists of a Fe (II) and a-ketoglutarate-dependent dioxygenase. ALKBH5 directly catalyzes the oxidative demethylation of m6A-methylated adenosine. ALKBH5 involves in tumorigenesis and tumor progression, and is often dysregulated in a wide range of cancers, including colorectal cancer. Emerging evidence indicates that the expression of ALKBH5 is associated with the abundance of infiltrating immune cells in the microenvironment. However, how ALKBH5 affects immune cell infiltration in the microenvironment in colorectal cancer (CRC) has not been reported. The aim of this study was to identify how the expression of ALKBH5 affects the biological behaviors of CRC cell lines and regulates the effects on infiltrating CD8+ T cells in CRC microenvironment with its specific mechanism.
METHODS: Firstly, the transcriptional expression profiles of CRC were downloaded from TCGA database and integrated via R software (4.1.2). Between CRC and normal colorectal tissues, ALKBH5 mRNA expressions were compared (Wilcoxon rank-sum). We further identified the expression levels of ALKBH5 in CRC tissues and cell lines through quantitative PCR, western blot, and immunohistochemistry. Then, how ALKBH5 affects the biological behaviors of CRC cells were confirmed by gain- and loss-of-function analysis. Furthermore, the relationship between ALKBH5 level and 22 tumor-infiltrating immune cells was examined through CIBERSORT in R software. Furthermore, we explored the correlation between ALKBH5 expression and tumor-infiltrated CD8+, CD4+ and regulatory T cells by utilizing the TIMER database. Finally, the association between chemokines and CD8+ T cells infiltration in CRC was analyzed using GEPIA online database. qRT-PCR, WB and IHC were used to further determine the effect of ALKBH5 on NF-κB-CCL5 signaling axis and CD8+ T cells infiltration.
RESULTS: Clinically, ALKBH5 expression was downregulated in CRC and low levels of ALKBH5 expression were correlated with poor overall survival (OS). Functionally, overexpression of ALKBH5 reduced the proliferation, migration and invasion of CRC cells, and vice versa. Overexpression of ALKBH5 suppresses NF-κB pathway, thus reduces CCL5 expression and promotes CD8+ T cells infiltration in CRC microenvironment.
CONCLUSIONS: ALKBH5 is poorly expressed in CRC, and overexpression of ALKBH5 attenuates CRC malignant progression by inhibiting CRC cell proliferation, migration, invasion and promoting CD8+ T cells infiltration in the tumor microenvironment through NF-κB-CCL5 axis.

Keywords:  ALKBH5; CCL5; CD8(+) T cells; Colorectal cancer; NF-κB; Tumor microenvironment

DOI:  https://doi.org/10.1016/j.tranon.2023.101683
Diagnostics (Basel). 2023 May 11. pii: 1697. [Epub ahead of print]13(10):

Identification of m7G-Related LncRNA Signature for Predicting Prognosis and Evaluating Tumor Immune Infiltration in Pancreatic Adenocarcinoma.

Jiawei Lu, Pusheng Yang, Lanting Yu, Ni Xie, Ying Wu, Baiwen Li.

  N7-Methylguanosine (m7G) modification holds significant importance in regulating posttranscriptional gene expression in epigenetics. Long non-coding RNAs (lncRNAs) have been demonstrated to play a crucial role in cancer progression. m7G-related lncRNA may be involved in the progression of pancreatic cancer (PC), although the underlying mechanism of regulation remains obscure. We obtained RNA sequence transcriptome data and relevant clinical information from the TCGA and GTEx databases. Univariate and multivariate Cox proportional risk analyses were performed to build a twelve-m7G-associated lncRNA risk model with prognostic value. The model was verified using receiver operating characteristic curve analysis and Kaplan-Meier analysis. The expression level of m7G-related lncRNAs in vitro was validated. Knockdown of SNHG8 increased the proliferation and migration of PC cells. Differentially expressed genes between high- and low-risk groups were identified for gene set enrichment analysis, immune infiltration, and potential drug exploration. We conducted an m7G-related lncRNA predictive risk model for PC patients. The model had independent prognostic significance and offered an exact survival prediction. The research provided us with better knowledge of the regulation of tumor-infiltrating lymphocytes in PC. The m7G-related lncRNA risk model may serve as a precise prognostic tool and indicate prospective therapeutic targets for PC patients.

Keywords:  immune infiltration; lncRNA; m7G; overall survival; pancreatic adenocarcinoma; prognostic signature

DOI:  https://doi.org/10.3390/diagnostics13101697
DNA Cell Biol. 2023 May 25.

FTO Promotes the Stemness of Gastric Cancer Cells.

Mengqing Li, Xuan Wu, Guan Li, Guoqing Lv, Shubin Wang.

  The full name of the FTO gene is fat mass and obesity-associated gene. In recent years, it has also been found that FTO is involved in m6A demethylation and regulates the progression of multiple cancers, including gastric cancer. The cancer stem cell theory argues that cancer stem cells are key factors in cancer metastasis, and inhibiting the expression of stemness genes is a good method to inhibit metastasis of gastric cancer. Currently, the role of the FTO gene in regulating stemness of gastric cancer cells is still unclear. By analyzing public databases, it was discovered that FTO gene expression was increased in gastric cancer, and high expression of FTO was associated with poor prognosis of patients with gastric cancer. After gastric cancer stem cells were isolated, it was found that FTO protein expression was increased in gastric cancer stem cells; stemness of gastric cancer cells was reduced after the FTO gene knockdown; subcutaneous tumors of nude mice were smaller than those of the control group after FTO knockdown; and stemness of gastric cancer cells was enhanced after FTO was overexpressed by plasmid. By reviewing additional literature and experimental validation, we found that SOX2 may be the factor by which FTO promotes the stemness of gastric cancer cells. Therefore, it was concluded that FTO could promote the stemness of gastric cancer cells, and targeting FTO may be a potential therapeutic approach for patients with metastatic gastric cancer. CTR number: TOP-IACUC-2021-0123.

Keywords:  FTO; cancer; stemness

DOI:  https://doi.org/10.1089/dna.2023.0074
Cancer Cell Int. 2023 May 25. 23(1): 102

Hyperglycemia and O-GlcNAc transferase activity drive a cancer stem cell pathway in triple-negative breast cancer.

Saheed A Ayodeji, Bin Bao, Emily A Teslow, Lisa A Polin, Greg Dyson, Aliccia Bollig-Fischer, Charlie Fehl.

   BACKGROUND: Enhanced glucose metabolism is a feature of most tumors, but downstream functional effects of aberrant glucose flux are difficult to mechanistically determine. Metabolic diseases including obesity and diabetes have a hyperglycemia component and are correlated with elevated pre-menopausal cancer risk for triple-negative breast cancer (TNBC). However, determining pathways for hyperglycemic disease-coupled cancer risk remains a major unmet need. One aspect of cellular sugar utilization is the addition of the glucose-derived protein modification O-GlcNAc (O-linked N-acetylglucosamine) via the single human enzyme that catalyzes this process, O-GlcNAc transferase (OGT). The data in this report implicate roles of OGT and O-GlcNAc within a pathway leading to cancer stem-like cell (CSC) expansion. CSCs are the minor fraction of tumor cells recognized as a source of tumors as well as fueling metastatic recurrence. The objective of this study was to identify a novel pathway for glucose-driven expansion of CSC as a potential molecular link between hyperglycemic conditions and CSC tumor risk factors.
METHODS: We used chemical biology tools to track how a metabolite of glucose, GlcNAc, became linked to the transcriptional regulatory protein tet-methylcytosine dioxygenase 1 (TET1) as an O-GlcNAc post-translational modification in three TNBC cell lines. Using biochemical approaches, genetic models, diet-induced obese animals, and chemical biology labeling, we evaluated the impact of hyperglycemia on CSC pathways driven by OGT in TNBC model systems.
RESULTS: We showed that OGT levels were higher in TNBC cell lines compared to non-tumor breast cells, matching patient data. Our data identified that hyperglycemia drove O-GlcNAcylation of the protein TET1 via OGT-catalyzed activity. Suppression of pathway proteins by inhibition, RNA silencing, and overexpression confirmed a mechanism for glucose-driven CSC expansion via TET1-O-GlcNAc. Furthermore, activation of the pathway led to higher levels of OGT production via feed-forward regulation in hyperglycemic conditions. We showed that diet-induced obesity led to elevated tumor OGT expression and O-GlcNAc levels in mice compared to lean littermates, suggesting relevance of this pathway in an animal model of the hyperglycemic TNBC microenvironment.
CONCLUSIONS: Taken together, our data revealed a mechanism whereby hyperglycemic conditions activated a CSC pathway in TNBC models. This pathway can be potentially targeted to reduce hyperglycemia-driven breast cancer risk, for instance in metabolic diseases. Because pre-menopausal TNBC risk and mortality are correlated with metabolic diseases, our results could lead to new directions including OGT inhibition for mitigating hyperglycemia as a risk factor for TNBC tumorigenesis and progression.

Keywords:  Chemical biology; Epigenetics; Glycobiology; Hyperglycemia; Metabolic disease; O-GlcNAc transferase; Obesity; TET1; TNBC; Tumorigenesis

DOI:  https://doi.org/10.1186/s12935-023-02942-6
Front Oncol. 2023 ;13 1177120

Novel methylation-related long non-coding RNA clinical outcome prediction method: the clinical phenotype and immune infiltration research in low-grade gliomas.

Youjun Li, Xiaobo Li, Zhengtao Yu.

   Background: Recent studies have suggested that long non-coding RNAs (lncRNAs) may play crucial role in low-grade glioma; however, the underlying mechanisms linking them to epigenetic methylation remain unclear.
Methods: We downloaded expression level data for regulators associated with N1 methyladenosine (m1A), 5-methyladenine (m5C), and N6 methyladenosine (m6A) (M1A/M5C/M6A) methylation from the Cancer Genome Atlas-low-grade glioma (TCGA-LGG) database. We identified the expression patterns of lncRNAs, and selected methylation-related lncRNAs using Pearson correlation coefficient>0.4. Non-negative matrix dimensionality reduction was then used to determine the expression patterns of the methylation-associated lncRNAs. We constructed a weighted gene co-expression network analysis (WGCNA) network to explore the co-expression networks between the two expression patterns. Functional enrichment of the co-expression network was performed to identify biological differences between the expression patterns of different lncRNAs. We also constructed prognostic networks based on the methylation presence in lncRNAs in low-grade gliomas.
Results: We identified 44 regulators by literature review. Using a correlation coefficient greater than 0.4, we identified 2330 lncRNAs, among which 108 lncRNAs with independent prognostic values were further screened using univariate Cox regression at P< 0.05. Functional enrichment of the co-expression networks revealed that regulation of trans-synaptic signaling, modulation of chemical synaptic transmission, calmodulin binding, and SNARE binding were mostly enriched in the blue module. The calcium and CA2 signaling pathways were associated with different methylation-related long non-coding chains. Using the Least Absolute Shrinkage Selector Operator (LASSO) regression analysis, we analyzed a prognostic model containing four lncRNAs. The model's risk score was 1.12 *AC012063 + 0.74 * AC022382 + 0.32 * AL049712 + 0.16 * GSEC. Gene set variation analysis (GSVA) revealed significant differences in mismatch repair, cell cycle, WNT signaling pathway, NOTCH signaling pathway, Complement and Cascades, and cancer pathways at different GSEC expression levels. Thus, these results suggest that GSEC may be involved in the proliferation and invasion of low-grade glioma, making it a prognostic risk factor for low-grade glioma.
Conclusion: Our analysis identified methylation-related lncRNAs in low-grade gliomas, providing a foundation for further research on lncRNA methylation. We found that GSEC could serve as a candidate methylation marker and a prognostic risk factor for overall survival in low-grade glioma patients. These findings shed light on the underlying mechanisms of low-grade glioma development and may facilitate the development of new treatment strategies.

Keywords:  LncRNA; M1A/M5C/M6A; immune infiltration; low-grade glioma; prognostic model

DOI:  https://doi.org/10.3389/fonc.2023.1177120